Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/me2resh/apexyardnpx agentmods add skills/me2resh/apexyard/dfdWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/me2resh/apexyard/dfd)<a href="https://agentmods.dev/skills/me2resh/apexyard/dfd"><img src="https://agentmods.dev/badge/skills/me2resh/apexyard/dfd/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/me2resh/apexyard/dfd"><img src="https://agentmods.dev/badge/skills/me2resh/apexyard/dfd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium MCP Rug Pull · line 210 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00030 | $0.05456 |
| Opus 5.5 | $0.00012 | $0.02182 |
| Sonnet 5.5 | $0.00006 | $0.01091 |
| Haiku 4.5 | $0.00003 | $0.00546 |
Grade A, and why
dfd scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 358 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/dfd — Data Flow Diagram Extractor
Read .claude/rules/writing-standard.md. Use the controlled technical writing profile for the DFD
and accompanying explanation. Keep classifications and uncertainty explicit.
Reads a codebase (or a portfolio of codebases for system-wide DFDs) and produces a Data Flow Diagram showing external actors, processes, data stores, data flows, trust boundaries, and per-element data classifications. The DFD is the input to STRIDE threat modelling and to GDPR cross-border / DPA-coverage analysis.
This skill is the canonical DFD producer in the apexyard family. /threat-model and /compliance-check consume the DFD it writes instead of regenerating their own — see AgDR-0026 for the design rationale.
| Skill | Role |
|---|---|
/dfd (this skill) |
Produces the DFD — six-axis discovery + classifications + cross-repo trace |
/threat-model |
Consumes the DFD — STRIDE walk over each trust-boundary crossing |
/compliance-check |
Consumes the DFD's classifications — cross-border transfers + DPA coverage |
/c4 |
Static topology (different shape — system + containers, no data-flow semantics) |
/process (#256) |
Dynamic control flow — BPMN, anchor-scoped multi-repo trace (shares the _lib-multi-repo-trace.sh helper) |
Path resolution
Read the registry path via portfolio_registry, the per-project docs dir via portfolio_projects_dir, and the workspace dir via portfolio_workspace_dir from .claude/hooks/_lib-portfolio-paths.sh. Cross-repo discovery uses the shared _lib-multi-repo-trace.sh helper. Source both at the top of any bash block:
source "$(git rev-parse --show-toplevel)/.claude/hooks/_lib-read-config.sh"
source "$(git rev-parse --show-toplevel)/.claude/hooks/_lib-portfolio-paths.sh"
source "$(git rev-parse --show-toplevel)/.claude/hooks/_lib-multi-repo-trace.sh"
projects_dir=$(portfolio_projects_dir)
Defaults match today's single-fork layout. Adopters in split-portfolio mode override the portfolio.* keys in .claude/project-config.json — the helper resolves whichever mode they're in. See docs/multi-project.md.
What ships with it
9 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- classify.sh 13 KB runs code
- discover.sh 14 KB runs code
- generate-dragon.sh 6.8 KB runs code
- generate-mermaid.sh 6.7 KB runs code
- lint.sh 405 B runs code
- tests/README.md 2.8 KB
- tests/smoke.sh 25 KB runs code
- tests/test_dfd_heading_contract.sh 5.6 KB runs code
- tests/test_generate_mermaid_heredoc.sh 3.8 KB runs code
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago Changed · +3 lines 21d36ad2c474
- 22d ago Changed · +1 lines e93eb4b97f1c
- 1mo ago Changed · +3 lines 2a95bca1b8b3
- 1mo ago First seen · 351 lines · 30 tokens per session scan A ba00e131f3ca
dfd is a skill published in the GitHub repository me2resh/apexyard (533 stars, last pushed today), licensed MIT. It adds 30 tokens to every session and 5,456 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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